In general, in a power semiconductor element for large power control which is used to control wind power generation, an electric vehicle, a hybrid car, and the like, the amount of heat generation is great. Therefore, as a substrate on which the power semiconductor element is mounted, for example, a power module substrate, which includes a ceramic substrate formed from aluminum nitride (AlN), alumina (Al2O3), and the like, a circuit layer that is formed on one surface of the ceramic substrate, and a metal layer that is formed on the other surface of the ceramic substrate, has been widely used in the related art.
In addition, a power module substrate with heat sink, in which a heat sink is bonded to the metal layer side, is provided so as to efficiently dissipate heat that is generated from the semiconductor element that is mounted, and the like.
For example, Patent Document 1 discloses a power module substrate with heat sink in which a circuit layer and a metal layer of the power module substrate is constituted by aluminum or an aluminum alloy, the heat sink is constituted by aluminum or an aluminum alloy, and the metal layer and the heat sink are bonded by soldering or brazing.
In addition, Patent Document 2 discloses a power module substrate with heat sink in which a circuit layer and a metal layer which are formed from aluminum are respectively formed on one surface and the other surface of the ceramic substrate, a copper plate is disposed between the metal layer and the heat sink, and the metal layer and the copper plate, and the copper plate and the heat sink are respectively soldered.
In addition, Patent Document 3 discloses a power module substrate with heat sink in which a circuit layer and a metal layer of a power module substrate are constituted by aluminum or an aluminum alloy, and a heat sink is constituted by aluminum or an aluminum alloy. In the power module substrate with heat sink, a bonding material constituted by copper or a copper alloy is interposed between the metal layer and the heat sink, and the metal layer and the bonding material, and the bonding material and the heat sink are respectively subjected to solid-phase diffusion bonding.